Abstract:To understand the attractive effect of artificial reefs, the activity traits of fishes, and the feasibility of ultrasonic telemetry for fish research in artificial reef areas, 5 species of 9 common rock fishes (22.0 cm±3.5 cm; 314 g±186 g) in the Beibu Gulf were tagged and tracked within an artificial reef area between July 7 and September 8, 2017, using the Vemco position system(VPS). Eleven receivers (VR2Tx, Vemco, 69 kHz) were launched in the artificial reef area of Fangchenggang inshore and the transmitters (V9P-2x, Vemco, 69 kHz) were tied to the backs of fishes. Not all fishes had good position results, and only 3 fishes had data available for analysis of home range size using 95% minimum convex polygons (MCPs). Home ranges were between 12687.6 m2 and 17123.2 m2, and the MCPs showed the activity of fishes in the small ranges. The other 6 fishes had poor position results (between 0 and 14 locations), and although the signal could not be received by 3 or more receivers, the data still indicated that the fishes were moving near the reef area because the range of signal reception was only approximately 200 m in the artificial reef area. Three fishes with poor position results left the area during this study between 28 to 51 days and then retured. This indicated that the fishes preferred the environment of the artificial reef area. During the study, the activity of fishes showed certain depth change rules. The fish activity in the shallower layer was between 15:00-22:00, and fish activity occurred above the reefs during this time, and perhaps it is the optimum time frame to determine the quantity of resources of these fish species in this area. To ensure the accuracy of the results, we eliminated the effect of tide before the calculation of depth results. The method of ultrasonic biotelemetry has an intuitive feeling for fish activity, but the method is in an experimental stage in China. The high cost is one reason why it cannot be widely promoted; furthermore, in the current experiment it was difficult to achieve the desired effects. We hope to analyze effectiveness for fish attraction and daily activities of fishes to provide a reference for subsequent research, and accumulate experience for subsequent application of this method.
